Define surprise before selecting winners
The example uses analyst-consensus surprise: S = 100 × (A - E) / |E|, where A is the first reported EPS and E is a frozen pre-announcement consensus for the same fiscal period, currency, share basis, and accounting definition. This percentage is not standardized unexpected earnings (SUE). A historical seasonal earnings model or a volatility-scaled SUE measure would define a different experiment.
- Predefine a denominator floor. Here |E| must be at least 0.05 in the selected EPS currency units. This arbitrary research setting excludes unstable near-zero ratios and must be reported with the sample count.
- Do not compare adjusted consensus EPS with reported GAAP EPS, or basic EPS with diluted EPS, without an explicit reconciliation. A large computed difference can be a definition mismatch.
- Record how the consensus was formed and its cutoff time. An estimate published after the earnings release is unavailable for the original decision even if it refers to the correct quarter.
| Illustrative input | Calculation | Decision at a +5% threshold |
|---|---|---|
| Actual 1.20; estimate 1.00 | 100 × (1.20 - 1.00) / 1.00 = +20% | Qualifies for the long-only example. |
| Actual -0.10; estimate -0.20 | 100 × (-0.10 + 0.20) / 0.20 = +50% | A smaller loss is a positive surprise; still verify matching definitions. |
| Actual 0.02; estimate 0.00 | Percentage denominator is zero. | Exclude under this rule; do not substitute zero surprise. |
| Actual 1.20; estimate missing | No valid surprise can be computed. | Record missing consensus; do not carry forward a prior quarter. |